I use 25 watt hydor heaters in my 2.5g and they been going for year plus and they are small about 6" long?
But I did get one that was broken from the start but amazon refunded me.
-Sent from my Samsung Note, a "Phablet"
Yeah I saw the Hydors around the net,it looks pretty good for the cost. Amazon is great about replacement or if someone messes you over too. I like dealing with them.